Hardy daylilies provide dependable summer color in most climates. There is a variety in nearly any color desired, with many flowers featuring two or more colors in the form of variegations and spots on the petals. While daylilies tolerate some neglect, fertilizing properly at the right time helps encourage the plants to bloom fully throughout the summer season.
Determining the soil pH prior to planting helps ensure the daylilies grow well in the site. Soil pH measures the acidity and the nutrients in the soil. Testing kits, available from garden centers and extension offices, help determine the pH and the amount of amendments necessary for the bed. Daylilies prefer soil acidity between 6.0 and 6.5. A lime amendment applied in spring prior to planting at the rate recommended by the test helps bring the soil into the optimum range.
The first fertilization in daylily beds occurs before you plant the daylily roots in spring after the last expected frost date. Apply 2 to 3 lbs. of 13-13-13 fertilizer to every 100 square feet of bed supplies the necessary nutrients for the daylilies to establish healthy roots and foliage growth. New-bed fertilization depends on the existing nutrient quality of the bed, so the amount may need adjusted depending on the results of the soil test.
The first spring fertilization occurs in the second year after planting, as newly planted daylilies have already received the necessary spring nutrients from pre-planting fertilization. Application time coincides with the first appearance of new leaves in the lily bed. An application of 2 lbs. 5-10-15 or similar fertilizer per every 100 feet of bed provides the necessary nutrients to existing lily in beds in spring.
While not necessary, a second fertilizer application in midsummer helps provide additional nutrients in the soil so the plants remain productive through the rest of the summer months. Time the second application to take place in June or early July, as fertilizing too late in the summer encourages lush growth too close to fall frost, which results in damage to the tender new plant growth. Summer fertilization types and amounts are the same as those applied in spring to established beds.